1. Field of the Invention
The invention relates to a unit of a piston and a piston rod of a longitudinally adjustable gas spring, comprising a piston rod, a piston and a gas-proof connection between the piston and the piston rod.
2. Background Art
In longitudinally adjustable gas springs having an actuating valve on the side of the housing opposite to the piston rod exit, the connection between the piston and the piston rod must be gas-proof in order for the two internal chambers separated from each other by the piston in the gas spring to be divided in a gas-proof manner. To this end a sealing is provided between the outside circumferential face and the internal wall of the associated housing. Additional sealings must be provided between the piston rod and the piston, since the piston is formed as an annular disk passed through by a peg-shaped end of the piston rod riveted to the piston rod. This structure is generally known in the longitudinally adjustable gas springs as they are widely spread, for instance from U.S. Pat. No. 3,656,593 or from U.S. Pat. No. 5,141,210. These units imply vast constructional expense; there is no precluding these units from becoming leaky during operation, as a result of which the gas spring concerned becomes unusable.